There is a need in the area of solvent dispersion of organic pigments for products of lower viscosity and improved transparency and gloss. This is particularly true in the area of solvent inks designed for packaging applications. The solvents used for this type of application include the oxygenated types such as alcohols (ethanol, propanols), esters (ethyl acetate, ispropyl acetate) and ethers (mono methyl ether of propylene glycol), or mixtures of such solvents. Typical resins dissolved in these solvents are nitrocellulose, polyamide, polyurethane or polyvinyl butyrate.
U.S. Pat. Nos. 4,057,436 and 4,518,435 disclose that dispersions of greatly increased fluidity can be produced by use of certain salts formed by the reaction between amines or quaternary ammonium salts and colored acids. However, these salts are not alkoxylated and are limited to the tertiary and quaternary amine types.
U.S. Pat. No. 6,471,764 discloses a method for enhancing the performance of a pigment composition containing an organic pigment, comprising enhancing the dispersion of said pigment by adding to 100 parts of said pigment about 1 to 30 parts of a specific pigment's etheramine sulfonic acid salt. However, the etheramine sulfonic salt disclosed is different than the one described hereinbelow which leads to inconsistent improvement in performance at least with regard to improvement in transparency as indicated in Table 2 of this patent.
The present invention provides for ink bases with excellent flow with good gloss and improved transparency over the ink bases of the prior art.